The Saucer bug

Saucer bugIlyocoris cimicoides
Head and front legs

GOOD CHANCE YOU FIND A FEW OF THIS BUGS in your dipping net
after one single scoop, provided the ditch has enough water plants. They are not as common as
the Lesser water boatmen and backswimmers, but in some waters they swarm. Yet you may not see them at
first: Saucer bugs are shy and hide in the water plants. But they are very good swimmers, and
when swimming look like water beetles with a dark back and a silver shimmering underside,
because of a small sheet of air on the abdomen.

At the surface
Hind leg

When he's out of the water the Saucer bug is able to walk well, in the pond net he crawls
quickly, sliding as if it were, under some leaves or in a safe corner. This bug needs some
supporting vegetation in the water, because though the insect is able to refresh it's air
supply by bringing the tip of the abdomen to the surface like a diving
beetle , the Saucer bug cannot keep a stable position there, as those beetles can. That's
why this bug dangles rather awkwardly below the surface in your jar with pond water, after
swimming round panicky. Add some plants or sticks and he is much more comfortable. Even more so
in a small aquarium with ground and plants, where Ilyocoris clings to the bottom, that
is if he doesn't crawl away between the vegetation. Now we can take a closer look.

APPEARANCE Seen from
above the shape of the body is oval, but in side view it is rather flat, like that of many
bugs. Many people feel an instinctive repulsion against flat insects. If we can overcome that,
we find this bug is beautifully adapted to its life habits. The underside has a layer of short
hairs which hold a sheet of air when under water. This air layer, which renders a silvery
glimmer to the abdomen, is part of the breathing air supply for the insect - though some
investigators think it's just there for a hydrostatic balance, a bit like the swim bladder of a
fish. There's another supply of air: the space between the elytra (hardened wings) and
the abdomen. The hind legs have broad fringes of swimming hairs that yield more power by
creating a larger surface, they provide the animal with two powerful paddles. The head is
streamlined with a smooth, round shape. The eyes seem to give the insect an aggressive
expression. )² The front legs are remarkable, they have the appearance of
the scissors of a lobster. The femur ("thigh") is broadened by the powerful muscles
within and has a groove. The tibia and tarsus(foot) are merged to a single claw,
that can be pressed in the groove to form a merciless trap. The grim purpose of this
construction may be clear: a small animal that gets caught in these sharp claws will never
escape alive. The front legs look much like the deadly sucking jaws of the larva of the great diving beetle. But the claws of the Saucer
bug are not hollow, and not used for sucking out it's prey, instead it stabs its razor sharp beak in
them, then toxic digestive saliva is injected in the wound, after which the dissolved body
parts are sucked in. This process is continuously repeated during the feeding process. In a
human finger this toxic injection needle may also penetrate deep. Many investigators felt it
was worse than the sting of a wasp, yet others wrote that the pain is intense, but short. Under
the elytra, the outer wings or front wings, all Saucer bugs have hind wings of normal
length. Whether they are able to fly is not certain. The wings may also have a function in
sealing the airspace between the elytra and the abdomen. In spring the males seem to be
able to produce tones with there abdomen. After mating, during which the male sits in a slanted
left position on the female, the eggs are injected in water plants. That makes them difficult
to find.

The nymph Saucer bug nymph

Below the surface

As with all Hemipterae (bugs) the nymph already closely resembles the perfect
insect. It has no wings and is rather transparent. The bright red eyes, contrasting with the
light green body make it look a bit more attractive. Of course is it as predaceous as the adult
Saucer bug. Yet I've never seen one catch a suitable prey, even if it was right under there
beak. Could it be they only hunt in the dark? They are rather vulnerable as well: in the
aquarium they often died after a few days, even though there was plenty of food. The nymphs are
flatter and more transparent then the full grown Saucer bug. On the picture on the right you
can see the transparent body. Clicking on that picture will show you an enlargement and some more
pictures of this specimen.

The scientific name for the Sauce bug is Ilyocoris cimicoides, sometimes you may find
the older name Naucoris cimicoides which is now discontinued.

All pictures on this site were made by Gerard Visser (Almelo,
Netherlands), unless stated otherwise. All rights remain with him. These pictures may not be
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